C-Scan
A C-scan is a plan-view ultrasonic display showing peak signal amplitude (color-coded) at every (X, Y) probe position across the inspected surface, producing a top-down map of internal flaws or wall loss.
Definition
A C-scan presents inspection data as a 2D plan view: the probe is scanned over an X-Y grid, and the peak signal amplitude (or time-of-flight) within a chosen gate is plotted as color at each grid point. The result is a top-down map of the inspected volume.
Technical Context
C-scans are essential for corrosion mapping, composite delamination imaging, and any inspection where the spatial extent of damage matters as much as its severity.
When It Is Used
- Pressure-vessel and tank corrosion mapping
- Composite and bondline imaging
- Forging laminations
What it represents
A plan-view ultrasonic image: amplitude or depth mapped over the scanned surface, built from encoded probe position. Where the A-scan is a waveform and the B-scan a cross-section, the C-scan is the map.
How it is derived
Corrosion mapping and composite inspection live on it — extent and pattern of damage are visible at a glance, and successive scans of the same area make growth measurable rather than anecdotal.
Where it is defined
ASME Section V Article 4 encoded-scanning provisions; corrosion-mapping procedures under API 510/570 programmes.
How it is misread
Reading a C-scan without knowing its gating. The image shows only what the gate was set to capture; damage outside the gate simply does not appear, however vivid the map looks.
Where C-Scan fits in an inspection programme
A term is only useful when it connects to a decision. C-Scan appears in written procedures, in technique sheets, and in the records an owner or accreditation body reviews afterwards — which means the way it is defined in your documentation has to match the way it is applied on site. Where the two drift apart, audits find it. Atlantis writes and reviews procedures against the governing codes, trains inspection personnel to apply them, and builds the record-keeping that makes the evidence retrievable years later. Procedure development and code consulting · NDT training and certification · Ask us about your programme.
Related terms
- A-Scan — An A-scan is the basic ultrasonic display showing signal amplitude (vertical axis) versus time-of-flight (horizontal axis) from a single transducer position, used to identify, size, and locate reflectors.
- B-Scan — A B-scan is a cross-sectional ultrasonic display showing depth (vertical) versus probe position along the scan axis (horizontal), with signal amplitude encoded as brightness or color, used for thickness profiling and corrosion mapping.
- Ultrasonic Testing (UT) — Ultrasonic Testing (UT) is an NDT method that uses high-frequency sound waves (typically 0.5–25 MHz) to detect internal flaws and measure thickness in metals, plastics, and composites by analyzing reflected echoes from a transducer.
More data terms
D-Scan · S-Scan · L-Scan · Distance-Amplitude Correction · Distance-Gain-Size · Time-Corrected Gain · Gating · Decibel · Indication · False Indication
Where this comes up in practice
Terms like this one appear in three places that matter commercially: the written practice that governs how your personnel are qualified, the procedures and technique sheets that define how an examination is actually performed, and the evidence an auditor or client asks for when they want to know why an inspection was accepted. Getting the terminology right is the easy part; being able to produce the qualification record, the calibration traceability and the procedure revision that applied on the day of the inspection is the part that decides audits.
Atlantis NDT provides NDT training and certification against ASNT SNT-TC-1A and ISO 9712, ASNT Level III consulting for written practices and procedure approval, inspection management software that holds qualification, calibration and procedure-revision evidence in recoverable form, and an asset integrity platform that binds inspection results to the asset they describe. Browse the full NDT glossary or ask a Level III directly.